CHATTANOOGA, Tenn. -- The Tennessee Valley Authority has reported finding elevated levels of radioactive tritium in a groundwater sample from a new onsite monitoring well at the Sequoyah Nuclear Plant near Chattanooga.

TVA said in an email Tuesday that the elevated levels pose no threat to public health and safety.

Sequoyah plant manager Paul Simmons said new groundwater monitoring wells were placed in an area known to have contained tritium that was previously reported.

The highest level found in the sampling on Friday was about 23,000 picocuries per liter. A "curie" is the standard measure for the intensity of radioactivity contained in a sample. A picocurie is one-trillionth of a curie.

TVA said there were no detectable levels of tritium in any sampling of the Tennessee River where the plant discharges water.